The invention relates to an electric machine having a frame to which a stator is secured, a rotor shaft carrying a rotor which cooperates electromagnetically with the stator, and a bearing arrangement for the rotor shaft. A thrust block can be screwed into the frame, and first and second magnetic means which cooperate with one another are provided to urge a bearing member which is connected to the rotor shaft so as to be rotatable thereby against a bearing surface of the thrust block. The thrust block is the first magnetic means and the rotor shaft is provided with the second magnetic means.
Japanese Kokai 57-160346 discloses an electric motor in which the rotor shaft is supported in ball-bearings, one end of the rotor shaft being pressed against a bearing surface of a thrust block. The pressure is provided by a magnetic force which acts between a first annular permanent-magnet secured to the rotor shaft and a second annular permanent magnet which is supported by the thrust block.
A drawback of the known motor is that the use of two magnets results in a comparatively expensive construction. Moreover, the magnets are annular which from the point of view of production engineering has the disadvantage that such magnets are difficult to manufacture. This is in particular so when the magnets are made of a high-grade material such as samarium-cobalt.